Recently, an electric power steering apparatus has been proposed, which includes an electric motor in a vehicle steering system and assists a driver with his or her steering force by use of power of the electric motor. A technique for preventing a failure of the electric motor used in the power steering apparatus has also been proposed.
For example, an electric power steering apparatus disclosed in Patent Literature 1 includes a unit that determines, when an average current is equal to or more than a predetermined value, a maximum limitation value that decreases by a predetermined value at predetermined intervals and a motor current limitation unit that limits the motor current by the maximum limitation value.